The chairman of a House panel investigating the deadly 2012 attacks in Benghazi, Libya, complained Tuesday that his committee should have received emails between Democratic presidential candidate Hillary Rodham Clinton and a longtime Clinton confidant long ago.

The confidant, Sidney Blumenthal, testified in a closed session before the House Benghazi committee Tuesday morning about frequent emails on Libya he sent to Clinton when she served as secretary of state. Blumenthal worked in the White House under President Bill Clinton and is a longtime friend and adviser to the Clinton family.

The committee announced Monday night that it had received roughly 60 new emails totaling 120 pages from Blumenthal. The emails are between Clinton and Blumenthal and were not previously produced to the committee or released to the public, a committee spokeswoman said.

"I will leave it to you to figure out whether there was a failure to produce on the former secretary's part or a failure to produce on the Department of State's behalf,'' Rep. Trey Gowdy, R-S.C., told reporters before the start of Tuesday's deposition. "But clearly the committee should have gotten this information sooner.''

Blumenthal's role in sending the near-monthly missives emerged when nearly 350 pages of emails about the 2012 attacks on the U.S. diplomatic post in Benghazi were publicly released last month. The attacks killed four Americans, including U.S. Ambassador Chris Stevens.

Democratic presidential candidate Hillary Rodham Clinton addresses an audience during a campaign stop at a Flag Day dinner, June 15, 2015, in Manchester, N.H.

His testimony comes days after Clinton formally kicked off her presidential campaign on Saturday.

"Given the volume and frankly the details of the correspondence between this witness and former Secretary Clinton, it's important for the committee to probe the depth, breadth and frankly the reliability of that information that he passed on,'' Gowdy said.

State Department spokesman Alec Gerlach said the department has worked to make public all of the emails received from Clinton.

"We provided the committee with a subset of documents that matched its request and will continue to work with them going forward,'' Gerlach said in an email. "Secretary (John) Kerry has been clear that the State Department will be both transparent and thorough in its obligations to the public on this matter.''

"Blumenthal offered a flood of advice and intelligence to his former boss, sending frequent emails about the growing unrest in Libya to the personal email account Clinton continued to use as a government employee. The correspondence, which covered everything from warring Middle Eastern factions to political strategy, was absorbed by Clinton, who often forwarded the messages to aides.

Clinton's earlier efforts to hire Blumenthal, who has spent nearly two decades working for the Clinton family, as a State Department employee were rejected by White House aides. Those aides feared that Blumenthal's role spreading harsh attacks against Barack Obama in the 2008 presidential primaries would cause discomfort within the Obama administration.

Rep. Lynn Westmoreland, R-Ga., said he and other committee members want to know the depth of Blumenthal's involvement in Libya policy, why he had the information and who gave it to him.

The five Democrats on the Benghazi panel said their Republican colleagues were no longer interested in discovering facts about Benghazi, but merely were trying to prove that Clinton ``engaged in some sort of conspiracy'' over the attacks.

Rep. Elijah Cummings, D-Md., the senior Democrat on the panel, said Blumenthal's deposition was the latest example of how the committee ``has strayed far from investigating the Benghazi attacks and is now focused like a laser on attacking Secretary Clinton in her run for president.''

Cummings called it a "travesty'' that the committee has spent more than $3.5 million on what he called a "partisan fishing expedition with no end in sight.''

Blumenthal was willing to testify yet was served with a subpoena by armed marshals, Cummings said. He called the subpoena, issued by Gowdy, "abusive'' and difficult to understand.

A federal judge has ordered the State Department to release batches of Clinton's email correspondence from her time as the nation's top diplomat every 30 days starting on June 30.